Nutritional status and dietary manipulation in predialysis chronic renal failure patients

OBJECTIVE: A properly implemented dietary treatment for patients with chronic renal failure (CRF) can correct several metabolic and endocrine disturbances and delay initiation of dialysis, but concerns exist about the risk of malnutrition and protein depletion. The goal of this study is to evaluate nutritional status and its relation to the dietary treatment in patients with advanced CRF. DESIGN: Cross-sectional survey. SETTING: Predialysis outpatient clinic. PATIENTS: Seventy patients (43 males, 27 females, 50 +/- 12 years) with severe CRF (glomerular filtration rate [GFR] <15 mL/min) being treated with a low-protein (0.6 g/kg/day) diet (LPD) or a very-low-protein (0.3 g/kg/day) diet supplemented with essential amino acids and ketoacids (KAD). Fifty-two healthy subjects with comparable age and sex served as controls. MAIN OUTCOME MEASURES: In all patients and controls, we performed biochemistry, anthropometry, bioelectrical impedance vector analysis (BIVA), and subjective global assessment (SGA), and the patients' outcomes were also assessed. RESULTS: Values of anthropometry and BIVA were similar in patients and controls. SGA scores showed a normal nutritional status (SGA-0) in 50 patients (71.4%) and mild to moderate SGA abnormalities (SGA-1) in 20 patients (28.6%); none had severe malnutrition. The SGA-1 patients differed from the SGA-0 patients by having higher serum urea, lower bicarbonate, and lower renal function (87% of SGA-1 patients had GFR <10 mL/min.). At the same GFR values (6.6 +/- 2.3 versus 6.6 +/- 2.3 mL/min) SGA-1 patients had lower bicarbonate (21.9 +/- 4.3 versus 25.3 +/- 2.7 mM, P <.01) and higher serum urea (115 +/- 29 versus 82 +/- 38 mg/dL, P =.01) and protein intake than SGA-0 patients; SGA-1 score was more prevalent with LPD compared with KAD treatment (45% versus 27%, P <.05). BIVA and anthropometry, serum levels of albumin, prealbumin, insulin-like growth factor-1, hematocrit, and lymphocyte count did not differ between SGA-1 and SGA-0 patients, but the number entering dialysis was higher in the group scoring as SGA-1 compared with SGA-0 (82% versus 47%, P <.05). CONCLUSIONS: With a planned dietary regimen, severe or overt malnutrition does not occur in predialysis CRF without other serious illnesses. However, some mild to moderate SGA abnormalities were detected in association with a more severe renal insufficiency, a lower serum bicarbonate, a higher serum urea and dietary protein levels and were predictive of poor renal outcome. This study emphasizes the role of proper dietary implementation, correction of metabolic acidosis, and clinical monitoring including SGA in the predialysis conservative care of CRF patients.